Gyro wave activated power generator and a wave suppressor using the power generator

ABSTRACT

A gyro wave-activated power generator utilizing wave energy which has, as a component, a control moment gyro, and which comprises a floating body ( 1 ), a control moment gyro ( 5 ) supported by the floating body, and a power generator ( 10 ) connected to the gimbal shaft of the gyro through a gearing to increase speed( 9 ), and is characterized by the gimbal ( 6 ) of the gyro being rotated by the movement of the floating body by wave energy to drive the power generator ( 10 ) for power generation.

FIELD OF TECHNOLOGY

The present invention relates to a gyro wave-activated power generatorutilizing wave energy which has, as a component, a control moment gyro.

BACKGROUND ART

Global environmental problems including global warming are recentlybeing seriously studied throughout the world. It is necessary toactively promote the use of clean natural energy.

The use of natural energy typically includes photovoltaic powergeneration, wind power generation, and wave-activated power generation.Photovoltaic and wind power generation are commercially available.However, the production of solar panels involves significant costs. InJapan, where earthquakes and typhoons frequently occur, wind powergeneration plants must be constructed with extra strength. Vast landareas are required to construct large-scale wind power generation farms.

As Japan is an island nation surrounded by the sea on all sides, wavepower generation is a promising energy source. Wave power generation isbeing actively studied in Japan but the technology has not yet reachedcommercial levels.

Various systems for wave power generation have been proposed andexperiments conducted. Many of these systems utilize the vertical motionof waves to create a flow of air or water, with the flow guided througha duct to rotate a turbine (Kokai Tokkyo Koho (Publication of unexaminedpatent applications) No. 6-280240 (1994) and 5-164036 (1993), etc.).Small-sized floating power generators based on these inventions havealready been put to commercial application as navigation aids.Experiments on large-sized floating wave power generators currentlyunderway include Kaimei (80 m in total length, 12 m in width, andweighing 800 tons) of the Japan Marine Science and Technology Centerand, the stationary type Sanze model (Research Development Corporationof Japan, etc.).

Wave-activated power generators using fluids, such as those mentionedabove, are generally inefficient at generating electric power because ofthe severity of existing conditions like wave magnitude. Improvingefficiency requires increasing the size of the system, which in turnmeans significant investments that the system uneconomical.

The present invention intends to solve the above problems by offering asmall-sized and efficient wave-activated power generator. According tothe present invention, the motion of a floating body on the sea isconverted into energy by a control moment gyro to generate power. A wavesuppressor using said power generator is also offered.

The wave-activated power generator of the present invention comprises anenclosed gimbal, a flywheel which is set in the gimbal and turns on thespin shaft that is mounted at right angles to the gimbal shaft, a spinmotor to turn the flywheel at high speed, and a power generatorconnected to the gimbal shaft via a gearing to increase speed, whereinthe motion of the floating body produced by wave action is used to turnthe gimbal to generate power. The system of the present invention isprovided with a sensor to detect the inclination and angular velocity ofthe floating body and an encoder to detect the rotational angle andposition of the gimbal. Signals from the sensor are used to synchronizethe motion of the floating body with the rotation of the control momentgyro body for more efficient power generation. The efficiency of powergeneration is further enhanced by matching the gimbal rotation to thewave motion, which is basically a circular motion.

DISCLOSURE OF THE INVENTION

The means of the technical solution offered by the present invention isa gyro wave-activated power generator that comprises a floating body, acontrol moment gyro supported on said floating body, and a powergenerator connected to the gimbal shaft of said gyro via gearing toincrease speed, wherein the motion of the floating body produced by waveaction is used to turn the gimbal of said gyro to generate power.

The present invention further intends to provide a gyro wave-activatedpower generator wherein multiple control moment gyros are set on saidfloating body to generate power from each of the respective gyros.

The present invention also intends to provide a gyro wave-activatedpower generator wherein ballast water is pumped into said floating bodyto change the natural frequency of the floating body to synchronize itsfrequency with the wave frequency.

The present invention also intends to provide a gyro wave-activatedpower generator wherein the rotational speed of said gyro is controlledin such a manner that the rotation of the control moment gyro bodysynchronizes with the motion of said floating body.

The present invention also provides a wave suppressor wherein multiplegyro wave-activated power generators of the present invention arearrayed on the water surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the gyro wave-activated powergenerator of the present invention that comprises a control moment gyro,a power generator, and a controller;

FIG. 2 is an oblique view of the floating body used in the gyrowave-activated power generator of the present invention;

FIG. 3 is the control block diagram for the floating body of the gyrowave-activated power generator of the present invention;

FIG. 4 is the plan of a typical layout of an array of control momentgyros of the gyro wave-activated power generator of the presentinvention;

FIG. 5 is an illustration that describes a wave suppressor comprising anarray of multiple gyro wave-activated power generators of the presentinvention; and

FIG. 6 shows the relationship between wave height and power generatoroutput.

BEST MODE OF IMPLEMENTATION OF THE INVENTION

The gyro wave-activated power generator of the present invention, whichcomprises a control moment gyro, a power generator, and a controller, isdescribed below referring to the attached drawings.

FIG. 1 is a cross-sectional view of the first working example of thepower generator of the present invention. FIG. 2 is an oblique view ofthe floating body used in the present invention. FIG. 3 is the controlblock diagram. FIG. 4 is the plan of a typical layout of an array ofcontrol moment gyros of the present invention.

In FIG. 1, the main floating body (1), roughly square in shape,comprises two floating sub-bodies (1A) which are connected by twomembers (1B). The control moment gyro power generator, which isdescribed later, is positioned at the center of the bottom (2) of saidsquare floating body. The main floating body (1) is fixed to the seabottom with anchors (3). The main floating body (1) may not necessarilybe square in shape but may also be of any other shape that can resistpossible overturning, such as a ship-like, circular, or polygonal shape.

Two gimbal shaft bearings (4) are installed at the center of the bottom(2) of the main floating body (1) to support the control moment gyro (5)on both sides. The gimbal shafts (6 a and 6 b) of the control momentgyro (5) rest and turn freely on said gimbal shaft bearings (4). Thegimbal (6) is a sealed cylindrical vessel, in which a flywheel (7) ismounted and rotates freely on the spin shaft (7 a). Said spin shaft (7a) is installed at right angles to said gimbal shafts (6 a and 6 b). Aspin motor (8) is installed on the spin shaft (7 a) of the flywheel (7).The spin motor (8) is set within or on the outside of the vessel and issealed to prevent air from entering the vessel. The sealed vesselforming the gimbal (6) is connected to a vacuum pump (not shown). Thisnegative pressure pump is used to reduce the pressure inside the gimbal(6) to, for example, 0.1 atmospheric pressure or below to decreaseflywheel drag (7) and windage loss.

The gimbal (6) is connected, on the gimbal shaft (6 b) side, to thepower generator (10) via gearing to increase speed (9) that comprises agear mechanism and others so that power is generated as the gimbal (6)rotates. The power generator (10) is connected, regardless of thedirection the gimbal (6) rotates, to a power converter (not shown) or abattery H. Kanki (not shown) via a compatible rectifier. The shaft (6 a)on the other side of the gimbal (6) accommodates the spin motor (8) andbrushes (11) that supply power to the vacuum pump motor. These units areconnected to a power supply. A brake may also be installed to stop theflywheel in the event of an emergency such as an accident. The powergenerator (10) is mounted on a base (12) on the bottom of the mainfloating body. The control moment gyro is similar to conventional unitsin terms of its basic structure and operation, and therefore adescription of its operating principle is omitted here.

The main floating body (1) is equipped with a controller (13) to controlpower and the power generator. The main floating body (1) is also fittedwith a pump (not shown) and a valve (not shown) to adjust the volume ofballast water pumped into the floating body. By adjusting the volume ofballast water, the natural frequency of the floating body can besynchronized with the wave frequency. The main floating body (1) is alsoprovided with a motion sensor (14) to detect the inclination and angularspeed of the main floating body (1) and an encoder (15) (a sensor todetect the direction of the gimbal shaft) to detect the angle ofrotation and the position of the gimbal (6). These sensors areelectrically connected to the controller (13) mounted on the mainfloating body (1).

The generator and other equipment mounted on the main floating body (1)are protected from sea water spray and splashing by a cover (16).

The following is a description of the operation of the gyrowave-activated power generator constructed as detailed above.

The gyro wave-activated power generator is set on the sea surface withthe flywheel (7) driven by the spin motor (8) and rotating at highspeed. The motion (inclination) of the main floating body (1) caused bywave action is transferred to the control moment gyro (5) to turn thegimbal (6) and drive the generator (10) via gearing to increase speed(9) to generate power. The generated power is stored in a battery H.Kanki or supplied directly to operate an actuator.

While power is being generated, the controller uses signals from themotion sensor (14) to detect the inclination and angular speed of themain floating body (1) and the encoder (15) (sensor to detect thedirection of the gimbal shaft) to detect the rotation angle and positionof the gimbal (6). The controller synchronizes the motion of thefloating body with the rotation of the control moment gyro body usingthe circuit shown in the control block diagram in FIG. 3. The speed ofthe gyro (6) is controlled on the generator side to generate power mostefficiently. Ballast water is pumped into the floating body (1) at acontrolled volume to synchronize the natural frequency of the floatingbody motion to the wave frequency to further enhance power generationefficiency. This system is particularly effective when wave magnitudeand frequency differ during the summer and winter seasons.

Software programs installed on a PC are used to control the powergenerator and volume of ballast water.

The power generating efficiency of the CMG system (gyro wave-activatedpower generation) of the present invention was compared with the outputfrom an existing floating body air turbine type system. The result of atypical example is shown below.

The efficiency values of the CMG system of the present invention wereobtained by synthesizing three stages of conversion efficiencies asfollows:

-   -   (1) First conversion efficiency from wave motion to floating        body motion: η₁=0.6 to 0.9    -   (2) Conversion efficiency from floating body motion to CMG        output shaft:        -   η₂=0.9 to 0.95    -   (3) Conversion efficiency from CMG output shaft to output of        electricity from the generator: η_(G)=0.8 to 0.9        The synthesized efficiency η_(T) was 0.43 to 0.77.

For evaluating existing floating body air turbine systems such as Kaimeiand Mighty Whales, the power generation efficiency was obtained bysynthesizing five stages of conversion efficiencies as follows:

-   -   (1) First conversion efficiency from wave motion to floating        body motion: η₁=0.6 to 0.9    -   (2) Conversion efficiency from floating body motion to water        column motion: η_(C)=0.8    -   (3) Conversion efficiency from water column motion to air        motion: η_(a)=0.9 to 1.0    -   (4) Conversion efficiency from air motion to turbine output:        η_(t)=0.3 to 0.6 (Wells Turbine)    -   (5) Conversion efficiency from turbine output to generator        output: η_(G)=0.8 to 0.9

The synthesized efficiency η_(T) was 0.10 to 0.39.

Stages (1) and (5) are common in both cases, indicating that the turbineis responsible for the deteriorated efficiency.

With the CMG system, the efficiency from the floating body motion to thegenerator input η₂ was 0.9 to 0.95 because only momentum conversion isinvolved with no loss other than mechanical loss. With the air turbinesystem, on the other hand, conversion takes place at three stages, withthe result that η₂=0.216 to 0.48, or approximately twice the level ofthe CMG system.

Relationship Between Wave Height and Power Generator Output

Frequency decreases with increasing wave height and conversely increasesat lower wave height. As a result, the output characteristics of thegenerator have the tendency shown in FIG. 6. With the CMG system, thedecrease in output is small even when wave height is low while theoutput is not too large when wave height is high. This stable output isfavorable for system operation.

In addition to the working of the present invention that has alreadybeen explained, it should be noted that multiple sets of control momentgyros as used in the present invention may be installed on a singlefloating body. FIG. 4, for example, shows a set of two gyros installedon the floating body in a different orientation to generate electricpower stably regardless of the wave direction.

Wave action is basically a circular motion. It is preferable to have thegimbal rotate in the same basic direction as said circular wave motionand set the gyro body at an angle to the incoming wave direction.

Two or more wave-activated power generators of the present invention maybe arrayed to form a sort of breakwater as shown in FIG. 5 to constructa wave suppressor that creates a calm sea area.

The present invention may be implemented in various other forms ofembodiment without deviating from the spirit of its main features. Theabove-mentioned embodiments are only a few examples and should not beconstrued as limiting.

INDUSTRIAL APPLICABILITY

As described in detail in the above paragraphs, the gyro wave-activatedpower generator of the present invention captures the motion of afloating body on the sea with a control moment gyro, and it generateselectric power efficiently using the captured energy. It is possible toreduce flywheel resistance in the gimbal by maintaining the inside ofthe sealed gimbal enclosure, a component of the present invention, at anegative pressure using a vacuum pump. This decreases the energy todrive the spin motor. Multiple sets of control moment gyros may beinstalled on a single floating body to prevent unwanted motion of thefloating body and generate electric power efficiently. Power generatingefficiency can be improved by synchronizing the natural frequency of thefloating body motion to the wave frequency by pumping ballast water intothe floating body at a controlled volume. Multiple floating bodiesequipped with power generators may be arrayed to form a sort ofbreakwater to be used as wave suppressor to create a calm sea area.These are some of the excellent effects of the present invention and itsembodiments.

1. A gyro wave-activated power generator comprising: a floating body,multiple control moment gyros supported by said floating body whereinsaid gyros are installed on said floating body in a differentorientation from each other, and a power generator connected to a gimbalshaft of each of said gyros via gearing to increase speed wherein agimbal of each of said gyros is rotated by the motion of said floatingbody produced by wave action which drives said power generator togenerate power.
 2. A gyro wave-activated power generator comprising: afloating body, a two or more control moment gyros supported by saidfloating body, and a power generator connected to the a gimbal shaft ofeach of said gyros via gearing to increase speed, wherein the gimbal ofeach of said gyros is continuously rotated in a circle by the motion ofsaid floating body produced by wave action which drives said powergenerator to generate power.
 3. A wave suppressor comprising multiplegyro wave-activated power generators as claimed in claim 2, wherein saidmultiple power generators are arrayed on the surface of the sea.
 4. Agyro wave-activated power generator as claimed in claim 2, wherein thegyro speed for each of said gimbals is controlled to synchronize themotion of the floating body with the rotation of the control momentgyros.
 5. A wave suppressor comprising multiple gyro wave-activatedpower generators as claimed in claim 4, wherein said multiple powergenerators are arrayed on the surface of the sea.
 6. A gyrowave-activated power generator as claimed in claim 2, wherein ballastwater is pumped into said floating body to synchronize the naturalfrequency of the floating body to the wave frequency.
 7. A wavesuppressor comprising multiple gyro wave-activated power generators asclaimed in claim 6, wherein said multiple power generators are arrayedon the surface of the sea.
 8. A gyro wave-activated power generator asclaimed in claim 6, wherein the gyro speed is controlled to synchronizethe motion of the floating body with the rotation of the control momentgyros.
 9. A wave suppressor comprising multiple gyro wave-activatedpower generators as claimed in claim 8, wherein said multiple powergenerators are arrayed on the surface of the sea.
 10. A gyrowave-activated power generator comprising: a floating body, a controlmoment gyro supported by said floating body, and a power generatorconnected to the gimbal shaft of said gyro via gearing to increasespeed, wherein the gimbal of said gyro is rotated by the motion of saidfloating body produced by wave action which drives said power generatorto generate power, and wherein ballast water is pumped into saidfloating body to synchronize the natural frequency of the floating bodyto the wave frequency.
 11. A gyro wave-activated power generator asclaimed in claim 10, wherein the gyro speed is controlled to synchronizethe motion of the floating body with the rotation of the control momentgyro.
 12. A wave suppressor comprising multiple gyro wave-activatedpower generators as claimed in claim 10, wherein said multiple powergenerators are arrayed on the surface of the sea.
 13. A gyrowave-activated power generator comprising: a floating body, multiplecontrol moment gyros supported by said floating body, each of whichgenerates power, and a power generator connected to the gimbal shaft ofeach of said gyros via gearing to increase speed, wherein the gimbal ofeach of said gyros is rotated by the motion of said floating bodyproduced by wave action which drives said power generator to generatepower, and wherein ballast water is pumped into said floating body tosynchronize the natural frequency of the floating body to the wavefrequency.
 14. A wave suppressor comprising multiple gyro wave-activatedpower generators as claimed in claim 13, wherein said multiple powergenerators are arrayed on the surface of the sea.
 15. A gyrowave-activated power generator as claimed in claim 13, wherein the gyrospeed is controlled to synchronize the motion of the floating body withthe rotation of the control moment gyro.
 16. A gyro wave-activated powergenerator comprising: a floating body, a control moment gyro supportedby said floating body, and a power generator connected to the gimbalshaft of said gyro via gearing to increase speed, wherein the gimbal ofsaid gyro is rotated by the motion of said floating body produced bywave action which drives said power generator to generate power, andwherein the gyro speed is controlled to synchronize the motion of thefloating body with the rotation of the control moment gyro.
 17. A wavesuppressor comprising multiple gyro wave-activated power generators asclaimed in claim 16, wherein said multiple power generators are arrayedon the surface of the sea.
 18. A gyro wave-activated power generatorcomprising: a floating body, multiple control moment gyros supported bysaid floating body, each of which generates power, and a power generatorconnected to the gimbal shaft of each of said gyros via gearing toincrease speed, wherein the gimbal of each of said gyros is rotated bythe motion of said floating body produced by wave action which drivessaid power generator to generate power, and wherein the gyro speed iscontrolled to synchronize the motion of the floating body with therotation of the control moment gyros.
 19. A wave suppressor comprisingmultiple gyro wave-activated power generators as claimed in claim 18,wherein said multiple power generators are arrayed on the surface of thesea.